51. What are the rules to define a variable name in R programming language?
A variable name in R programming language can contain numeric and alphabets along with special characters like dot (.) and underline (-). Variable names in R language can begin with an alphabet or the dot symbol. However, if the variable name begins with a dot symbol it should not be a followed by a numeric digit.
52. What do you understand by a workspace in R programming language?
The current R working environment of a user that has user defined objects like lists, vectors, etc. is referred to as Workspace in R language.
53. Which function helps you perform sorting in R language?
Order ()
54. How will you list all the data sets available in all R packages?
Using the below line of code-
data(package = .packages(all.available = TRUE))
55. Which function is used to create a histogram visualisation in R programming language?
Hist()
DATA SCIENCE TRAINING
Weekend / Weekday Batch
56. Write the syntax to set the path for current working directory in R environment?
Setwd(“dir_path”)
57. How will you drop variables using indices in a data frame?
Let’s take a dataframe df<-data.frame(v1=c(1:5),v2=c(2:6),v3=c(3:7),v4=c(4:8))
df
## v1 v2 v3 v4
## 1 1 2 3 4
## 2 2 3 4 5
## 3 3 4 5 6
## 4 4 5 6 7
## 5 5 6 7 8
Suppose we want to drop variables v2 & v3 , the variables v2 and v3 can be dropped using negative indicies as follows-
df1<-df[-c(2,3)]
df1
## v1 v4
## 1 1 4
## 2 2 5
## 3 3 6
## 4 4 7
## 5 5 8
58. What will be the output of runif (7)?
It will generate 7 randowm numbers between 0 and 1.
59. What is the difference between rnorm and runif functions ?
rnorm function generates “n” normal random numbers based on the mean and standard deviation arguments passed to the function.
Syntax of rnorm function –
rnorm(n, mean = , sd = )
runif function generates “n” unform random numbers in the interval of minimum and maximum values passed to the function.
Syntax of runif function –
runif(n, min = , max = )
60. What will be the output on executing the following
R programming code – mat<-matrix(rep(c(TRUE,FALSE),8),nrow=4)
sum(mat)
8
